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A few weeks back, I purchased and tested the Curt BetterWeigh. This is a small device that plugs into your vehicles OBDII port, and will allow you to “weigh” your vehicle without going to visit a scale. I thought it was a super cool idea. Unfortunately, I couldn’t get it to work properly, and I said as much in the video. Well, the folks at Curt saw the video, contacted me, and then sent out a couple of engineers to try to figure out the problem.
So put yourself in Stef’s shoes for a minute. I imagine her thoughts went something like this: “James was mentioning something about his van-weighing-physics-gadget and OH MY GOD NOW THERE’S THREE OF THEM and they want me to videotape them.” The end result is this video:
First off, I appreciate Curt sending out Jacob and Thomas to try to get to the bottom of the ProMaster /BetterWeigh accuracy. Especially since my initial review of the BetterWeigh wasn’t all that positive!
OK. Now, on to what happened. I’ll try to keep it brief here. If you want the full details, you’ll just have to watch the video.
- Curt had developed a new calibration for the ProMaster and built it into their app. We tried this first, but got inconsistent results.
- Next, we made multiple runs in Lance with the guys from Curt gathering data for later analysis.
- Then, we tried a new way to mount the BetterWeigh to rule out any mounting peculiarities as the source of the inconsistencies. (We were able to rule it out. The mounting change had no impact.)
- The guys from Curt then borrowed Lance for a couple hours gathering additional data to take back with them.
- After analyzing the data, they developed a new calibration and uploaded it into their cloud.
The data analysis and developing a new calibration took a while. Even when they were done, they told me that there seems to be some data inconsistency with ProMasters in general (and Travatos in particular). They warned me to expect some issues with the data. Armed with this, I tried to weigh Lance again with the BetterWeigh.
The newest calibration and app produced mostly good results, but occasional “way-off” results. You can see the actual process in the video, but if you look at the results on a graph, it looks approximately like this:
So, if you know this, and are prepared to throw out the obviously inconsistent data, then it is possible to get a reasonable result from the BetterWeigh. At least that’s how it works in a ProMaster. It means you’d have to try to weigh more than once to be sure, but it CAN work.
This left me wondering if it was a problem only with the ProMaster, or if the inconsistent data extended to other vehicles as well. So, we tried again. The only other vehicle we had available right away was my Toyota Tacoma. It’s a 2018, and it’s not a terribly large truck, but it can tow, so it should be compatible with the BetterWeigh.
Unfortunately, we found that the Toyota Tacoma not only gave inconsistent results, but that none of these inconsistent numbers, even at random, had been accurate. (We weighed the Tacoma at the CAT scale. Probably the smallest thing they had seen all day.)
Not only were the weights way off, but the app was behaving strangely, which makes me think something was wrong. For example, the app made me “launch” twice each time to get a weight (instead of once, as in Lance). So I really think something was up with the Tacoma. Maybe they don’t have a good calibration for the Tacoma? Maybe there’s a problem with the Tacoma’s OBD port? I don’t know. I’ve fed this information back to the guys at Curt and we’ll see what they have to say.
Updates From Our Field Tester!!
Jacob and Thomas had left me with another BetterWeigh, which I passed on to one of our readers, Dan, who agreed to test the BetterWeigh on a different rig (his LTV Unity, on a Sprinter). Here’s what Dan reported back:
Thanks for sending me the BetterWeigh module which I received on the 19th.
After spending the good part of the afternoon yesterday attempting to pair the Bluetooth, I was about to call this device the “better – no way”. But after I deleted the app from my iPhone and reloaded it, it worked just fine.
To educate myself, I tried it on my F150 which I weighed last June on a Cat Scale. For some unknown reason to me, the correlation was terrible with the BetterWeigh. Again, I was about to abandon this “not-better weigh”.
However, the BetterWeigh worked exceptionally well with my LTV Unity Sprinter (see photo).
The average of 31 tests was 10,439 pounds compared with the Cat Scale weight of 10,415 pounds (see spreadsheet). This was a mere 0.2% difference. Also the variance of the test data was less than 5% which is acceptable considering that the rate of acceleration was provided by a human.
Today was fairly windy with winds in the range of 24 to 34 mph from the west. My premise was that wind should add to the demand on the engine torque and thus heavier apparent weights should be measured when driving into the wind. However, I drove north, south, east and west and couldn’t discern a trend.
Another factor that I investigated was the road quality and surface. Three of the roads were asphalt country roads (see photo) while the fourth (Fields Drive) was a new engineered concrete surface. Data points 23-31 were remarkably consistent for the concrete road.
In any case, I am satisfied with the experimental results. Please share them with whomever.
Daniel P. Abrams
Emeritus Professor of Structural Engineering
University of Illinois at Urbana-Champaign
So, is it a substitute for a “real” weight at a certified scale? No. Even working properly, the BetterWeigh only claims to be accurate within 5%. Depending on your rig, that 5% could be greater than your OCCC. But can it provide a useful rough approximation of your rig’s weight? Yes, potentially, depending on your vehicle. I suppose that’s a suggestion for Curt. Maybe they could post online somewhere a list of the vehicles they’ve calibrated and how many samples they’ve gathered for that vehicle. That could help a potential purchaser decide how well it might work for them. Given the dedication they’ve shown to getting this thing right, I have to imagine that if it doesn’t work for your vehicle, it can be made to work. This is the kind of product I could see getting better over time as they gather more data and more vehicle calibrations.
Anyway, that’s it for the Curt BetterWeigh.